Answer:
Part a
Null hypothesis:
![\mu = 69.3](https://img.qammunity.org/2021/formulas/mathematics/college/txt0jrff14xloala8ldz2v6bo637dizu1v.png)
Alternative hypothesis:
![\mu \\eq 69.3](https://img.qammunity.org/2021/formulas/mathematics/college/h2qbqqj3vrfj6u3yxpvzvze7ccims348jt.png)
Part b
![z = (69.8- 69.3)/((11.2)/(√(140)))= 0.528](https://img.qammunity.org/2021/formulas/mathematics/college/sk4nbca80jnnjxozo89omqsv6ez0l1sti6.png)
Explanation:
For this case we have the following info given :
the sample mean
represent the sample size
represent the standard deviation
Part a
And we want to test if the true mean is equal to 69.3 so then the system of hypothesis:
Null hypothesis:
![\mu = 69.3](https://img.qammunity.org/2021/formulas/mathematics/college/txt0jrff14xloala8ldz2v6bo637dizu1v.png)
Alternative hypothesis:
![\mu \\eq 69.3](https://img.qammunity.org/2021/formulas/mathematics/college/h2qbqqj3vrfj6u3yxpvzvze7ccims348jt.png)
Part b: Find the statistic
The statistic is given by:
![z= (\bar X - \mu)/((\sigma)/(√(n)))](https://img.qammunity.org/2021/formulas/mathematics/college/euhsjuu7ei5h0quaigp91mj303wr1f6qmd.png)
And replacing the info we got:
![z = (69.8- 69.3)/((11.2)/(√(140)))= 0.528](https://img.qammunity.org/2021/formulas/mathematics/college/sk4nbca80jnnjxozo89omqsv6ez0l1sti6.png)